[R-390] 390() vs 390(A), R-391

[William J.Neill]

I have 3 R-391's and one R-389 with working autotunes.  I also have 
caged squirrels on amphetamines that are a half-assed form of autotune 
for my 51J4.

Bill Neill
Conroe, Texas
On Thursday, December 30, 2004, at 04:42 , John KA1XC wrote:

>> Poll -- how many of you guys have R-391's with working autotuners?  How
> many
>> with non-working ones?  How many unknowns?  Actually, I think it was 
>> Paul
>> who rebuilt his '391, right?
>>
>> Barry
>
> Well Barry, I've got two of the 391 beasties, one has been given some
> attention and is working well as a 390, the other is still waiting in 
> line.
> Both were missing the locking keys and the state of the autotune is 
> TBD. On
> the one I worked on I did remove and open up the autotune boxes in the
> front - and yikes, talk about a box of complicated mechanical doodads. 
> They
> of course were smothered in old dried grease so I had some fun 
> scrubbing the
> mechanisms clean with WD-40 and oiling up the little oiler sponge 
> inside.
> That's about as far as I got, after that I re-installed them and told 
> myself
> I wouldn't attempt any further until I learned a lot more about how they
> work.
>
> I also thought the MC detent in the 391 was very well done; it is a much
> better engineered mechanism than the little spring steel weenie that 
> wears
> out in the 390 and 390A . Too bad they didn't use that design in all the
> radios.
>
> Without a functioning autotune I would say a R-391 is definitely second 
> to a
> R-390 in desirability due to the fact that the autotune mechanisms add 
> a lot
> of extra drag to the KC tuning. It gives you about 1/4 turn of easy 
> turning
> before it kicks in, and then the drag is much more noticeable.
>
> Another item lacking here is a good 28 VDC power supply with enough 
> oomph to
> drive the motor. Ideally what I'd like to get or build is a fully 
> metered
> regulated supply with adjustable current limiting, that way I'd set the
> current limit to just above what the motor normally draws and the power
> supply would go into current limit if something went wrong with the 
> autotune
> control and the motor hit a stop. It'd probably need at least 10,000 uF 
> on
> the supply output to take care of the motor start-up surge current too.
>
> Since I needed locking keys I bought a set from Hank Arney and they look
> real sweet. I tried inserting them into the knobs and into the innards 
> of
> the autotune and they thread in nice and smooth to a point but then 
> appear
> to bind up before the locking handle makes it down to flush with the 
> knob
> face. Is this normal or do they really need to be screwed in very hard 
> all
> the way down? Since I don't have any experience with using the autotune
> section I'm taking it real cautious here, don't want to beak anything! 
> I'd
> appreciate some advice on this.
>
> thanks,
> John
>
>
>
>
>
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